1. Field of the Invention
This invention relates to an internal combustion engine, and more particularly to a four cycle engine of the type including a crankshaft.
2. Description of Relevant Art
An outside member of an internal combustion engine is conventionally constituted either from four components including a cylinder head, a cylinder block and a crankcase consisting of a pair of symmetrical members, or from three components including an integral cast member presenting a cylinder block and a crankcase upper half, a cylinder head and a crankcase half. Accordingly, such a conventional internal combustion engine has various disadvantages to be eliminated or improved: it includes various components which are complicated in configuration, which results in an increase of fastening or binding parts such as bolts which are used in assembling these components; besides, mounting holes must be worked or drilled for individual ones of such components, which results in an increase of working and assembling operations; and hence production costs are inevitably increased; and so on.
The present invention has been thus made, on one hand, to improve such deficiencies of a conventional internal combustion engine, and with particular attention being paid to a structure of an internal combustion engine of the type including a cantilever type crankshaft.
Meanwhile, a four cycle engine including a vertically arranged crankshaft which is used as a general purpose engine and so on, commonly includes an oil lubricating mechanism and a governor mechanism. Since such an oil lubricating mechanism normally includes either an oil pump or an oil raking up blade wheel provided on a separate shaft for effecting lubrication of oil, it is disadventageous in that it requires an increased number of parts and makes the structure thereof complicated, and so on.
Accordingly, the present invention has been made, on the other hand, to improve these disadvantages of an engine which employs an oil raking up type lubricating system.
According to the present invention, there is provided a four cycle internal combustion engine of the type including a cantilever type crankshaft wherein it comprises an outside member including a cylinder block section and a crankcase half section which both are formed into a single body, the crankcase half section having at least a bearing portion for supporting the crankshaft thereon and being open in a direction of an axis of the crankshaft and also in a direction of an axis of an inner bore of a cylinder to define an opening which has an opening edge arranged in an inclined relationship to the center axis of the cylinder and also to the center axis of the crankshaft, and a crankcase half having an inclined opening edge corresponding to the opening edge of the crankcase half section for covering the opening of the crankcase half section.
According to another aspect of the invention, there is provided a four cycle internal combustion engine of the type including a vertically disposed crankshaft and a valve motion wherein it comprises a camshaft disposed perpendicularly to a shaft portion of the crankshaft and connected to the crankshaft such that it is driven by the crankshaft, and a governor slider of a speed governor mechanism provided on an end of the camshaft an including a raking up portion provided thereon for raking up oil.
It is an object of the present invention to provide a four cycle internal combustion engine of the type including a cantilever type crankshaft which includes an outside member whereby parts of complicated configuration can be decreased in number and hence reduction of the total number of components, facilitation of production and assemblage, and reduction of production costs can be easily attained.
It is another object of the invention to provide a four cycle internal combustion engine of the type including a vertically disposed crankshaft and a valve motion in which a structure for lubricating oil is simplified to improve the facility of production and assemlage of the same and hence reduction of production costs can be attained advantageously.
It is a further object of the invention to provide a four cycle internal combustion engine of the type including a cantilever type crankshaft which includes a crankshaft supporting structure which can assure an advantageous operation of the crankshaft by a simplified structure.